Survey of captive parrot populations around Port Phillip Bay, Victoria, Australia, for psittacine beak and feather disease virus, avian polyomavirus and psittacine adenovirus

Fluctuation of the prevalence of beak and feather disease virus in captive psittacines in Iran

Beak and feather disease virus (BFDV) is one of the most life-threatening viral agents infecting parrot species. In this study, we investigated fluctuation in the prevalence of beak and feather disease virus (BFDV) in captive psittacines in Iran. Two series of feather samples from different psittacine species, received between July 2019 and July 2021 (n = 1009) and between July 2021 and July 2022 (n = 2020), were examined for the presence of BFDV using the PCR method, and the host species distribution and temporal prevalence of BFDV within populations were calculated. The results showed a total viral prevalence of 26.86% and 26.88% within sample series 1 and 2, respectively. By examining both sample series, the prevalence of BFDV was found to be  the highest (P < 0.05) in Nymphicus hollandicus and the lowest (P < 0.05) in Psittacus erithacus, Myiopsitta monachus, Pyrrhura molinae, and Aratinga solstitialis. The viral prevalence was significantly higher (P < 0.05) within the series 1 than the series 2 samples only in Nymphicus hollandicus. Within series 2, the viral prevalence was significant (P < 0.05) in samples from Nymphicus hollandicus collected in March. This study indicates significant prevalence of BFDV in captive Nymphicus hollandicus populations and suggests that the fluctuation in the prevalence of BFDV could be due to the combined influence of host-species and temporal factors.

Australasian Pigeon Circoviruses Demonstrate Natural Spillover Infection

Pigeon circovirus (PiCV) is considered to be genetically diverse, with a relatively small circular single-stranded DNA genome of 2 kb that encodes for a capsid protein (Cap) and a replication initiator protein (Rep). Australasia is known to be the origin of diverse species of the Order Columbiformes, but limited data on the PiCV genome sequence has hindered phylogeographic studies in this species. To fill this gap, this study was conducted to investigate PiCV in 118 characteristic samples from different birds across Australia using PCR and sequencing. Eighteen partial PiCV Rep sequences and one complete PiCV genome sequence were recovered from reservoir and aberrant hosts. Phylogenetic analyses revealed that PiCV circulating in Australia was scattered across three different subclades. Importantly, one subclade dominated within the PiCV sequenced from Australia and Poland, whereas other PiCV sequenced in this study were more closely related to the PiCV sequenced from China, USA and Japan. In addition, PiCV Rep sequences obtained from clinically affected plumed whistling duck, blue billed duck and Australian magpie demonstrated natural spillover of PiCV unveiled host generalist characteristics of the pigeon circovirus. These findings indicate that PiCV genomes circulating in Australia lack host adapted population structure but demonstrate natural spillover infection.

First molecular detection of avian polyomavirus from captive psittacine birds in Bangladesh, together with confirmation of beak and feather disease virus co-infection

Avian polyomavirus (APV) is an emerging pathogen in many parts of the world responsible for causing significant mortality in captive psittacine birds. The virus spreads slowly, and transboundary movement of birds is one of the potential risk factors for the virus introduction in the naïve population. Bangladesh allows the import of birds, however there is currently no surveillance to screen for APV. Since we confirmed beak and feather disease virus (BFDV) infection in the captive population in our earlier investigation, we hypothesized that APV may also be circulating in Bangladesh. Feather samples were collected from 100 birds (90 psittacine and 10 non-psittacine). The polymerase chain reaction (PCR) was used to detect viral DNA together with sequencing and phylogenetic analysis. This first pilot study confirmed the presence (7%, 7/100) of APV in captive psittacine birds of Bangladesh and almost half (4%, 4/100) of the APV positive birds had the BFDV co-infection. All the PCR-positive birds were asymptomatic and found in live bird markets (LBMs). No significant variation was observed in the detection rate considering species (P = 0.94), age (P = 0.39) or sex (P = 0.55) of birds. According to the results of the phylogenetic study, the APV isolates found in Bangladesh appear to be unrelated to isolates from other geographical areas. These findings provide an evidence of APV circulating in Bangladesh, with or without the co-infection of BFDV. Additional studies are needed to investigate the occurrence of APV/BFDV co-infection in the larger population of Bangladesh and in countries where transboundary bird interaction with Bangladesh may be possible.

Investigation and sequence analysis of psittacine beak and feather disease virus and avian polyomavirus from companion birds in Windhoek, Namibia

The commercial farming and trading of parrots and ornamental birds as companion animals are important economic activities in many countries. Some of the bird species farmed/traded are captured from the wild or are closely related to wild birds and therefore represent a risk of pathogen exchange/introduction. Beak and feather disease virus (BFDV) and avian poliomavirus (APV) are among the viruses with the biggest impact on companion bird populations and have been detected in different hosts worldwide. Despite their relevance for both domesticated and wild birds, our knowledge of BFDV and APV epidemiology remains limited in several African countries. In the present study, 143 cloacal swabs were collected from companion birds in Windhoek, Namibia, and tested by polymerase chain reaction for BFDV and APV. Of the samples tested, 35/143 (24.48%) tested positive for BFDV; 11/143 (7.69%) were positive for APV; and 6/143 (4.2%) tested positive for both pathogens. Positive amplicons, consisting of segments of the ORF1 and VP1 genes, were sequenced and compared with sequences from viruses identified in other countries. Four Namibian-only clades of BFDV were identified, loosely related to foreign strains, which suggest the occurrence of multiple introduction events in the past, potentially from South Africa, followed by local, independent evolution. In contrast, the Namibian APV sequences were identical to each other and form a single clade. In both instances, no correlation was observed between the sampling host and the viral phylogeny, suggesting the absence of host-specific adaptation and a remarkable, unconstrained viral circulation within Namibian borders. Therefore, while regulations and control measures developed against foreign strain introduction have proven to be effective over time, the spread of BFDV and APV within Namibia's borders appears undeterred. Additional resources should be dedicated to limit strain circulation in commercial farming facilities, markets and small-scale traders.

Unexpected Pathogen Diversity Detected in Australian Avifauna Highlights Potential Biosecurity Challenges

Birds may act as hosts for numerous pathogens, including members of the family Chlamydiaceae, beak and feather disease virus (BFDV), avipoxviruses, Columbid alphaherpesvirus 1 (CoAHV1) and Psittacid alphaherpesvirus 1 (PsAHV1), all of which are a significant biosecurity concern in Australia. While Chlamydiaceae and BFDV have previously been detected in Australian avian taxa, the prevalence and host range of avipoxviruses, CoAHV1 and PsAHV1 in Australian birds remain undetermined. To better understand the occurrence of these pathogens, we screened 486 wild birds (kingfisher, parrot, pigeon and raptor species) presented to two wildlife hospitals between May 2019 and December 2021. Utilising various qPCR assays, we detected PsAHV1 for the first time in wild Australian birds (37/486; 7.61%), in addition to BFDV (163/468; 33.54%), Chlamydiaceae (98/468; 20.16%), avipoxviruses (46/486; 9.47%) and CoAHV1 (43/486; 8.85%). Phylogenetic analysis revealed that BFDV sequences detected from birds in this study cluster within two predominant superclades, infecting both psittacine and non-psittacine species. However, BFDV disease manifestation was only observed in psittacine species. All Avipoxvirus sequences clustered together and were identical to other global reference strains. Similarly, PsAHV1 sequences from this study were detected from a series of novel hosts (apart from psittacine species) and identical to sequences detected from Brazilian psittacine species, raising significant biosecurity concerns, particularly for endangered parrot recovery programs. Overall, these results highlight the high pathogen diversity in wild Australian birds, the ecology of these pathogens in potential natural reservoirs, and the spillover potential of these pathogens into novel host species in which these agents cause disease.

Evidence of circulation of beak and feather disease virus in captive psittacine and non-psittacine birds in Bangladesh

Beak and feather disease virus (BFDV) is an emerging pathogen in many parts of the world that is responsible for causing beak and feather disease in birds. Since the virus is highly persistent in the environment and spreads by contact, birds raised in captivity are at a high risk of infection. Breeding, trading, and rearing of captive birds are becoming increasingly popular in many countries, including Bangladesh, increasing the risk of BFDV infection. However, it is unknown whether BFDV is circulating in captive birds in Bangladesh. This study was designed to conduct the first pilot survey to test the hypothesis that BFDV is circulating in Bangladesh. Feather samples were collected from 100 birds of 10 psittacine and two non-psittacine species from a breeding flock, three live-bird markets (LBMs), and two household flocks. Polymerase chain reaction (PCR) was used to detect the rep gene, together with sequencing and phylogenetic analysis. This study confirmed that BFDV is circulating in Bangladesh, with a positivity rate of 37%. The majority (78.38%) of PCR-positive birds were asymptomatic. The detection rate was higher in birds from the breeding flock (54.05%) than in LBMs (37.84%) and household flocks (8.11%) (P = 0.01). No significant variation was observed when considering the species (P = 0.14) and sex (P = 0.75) of the birds. Phylogenetic analysis suggested that the BFDV isolates found in LBMs and household flocks are genetically related to isolates from breeding flocks in the area as well as to many other isolates from different regions of the world. Further research needs to be done to determine the impact of this virus in the wider population.

Meta-transcriptomic analysis of the virome and microbiome of the invasive Indian myna (Acridotheres tristis) in Australia

Invasive species exert a serious impact on native fauna and flora and have become the target of eradication and management efforts worldwide. Invasive avian species can also be important pathogen reservoirs, although their viromes and microbiomes have rarely been studied. As one of the top 100 invasive pest species globally, the expansion of Indian mynas (Acridotheres tristis) into peri-urban and rural environments, in conjunction with increasing free-ranging avian agricultural practices, may increase the risk of microbial pathogens jumping species boundaries. Herein, we used a meta-transcriptomic approach to explore the microbes present in brain, liver and large intestine of 16 invasive Indian myna birds in Sydney, Australia. From this, we discovered seven novel viruses from the families Adenoviridae, Caliciviridae, Flaviviridae, Parvoviridae and Picornaviridae. Interestingly, each of the novel viruses identified shared less than 80% genomic similarity with their closest relatives from other avian species, indicative of a lack of detectable virus transmission between invasive mynas to native or domestic species. Of note, we also identified two coccidian protozoa, Isospora superbusi and Isospora greineri, from the liver and gut tissues of mynas. Overall, these data demonstrate that invasive mynas can harbor a diversity of viruses and other microorganisms such that ongoing pathogen surveillance in this species is warranted.

Investigation and Sequence Analysis of Avian Polyomavirus and Psittacine Beak and Feather Disease Virus from Companion Birds in Eastern Turkey

Introduction

Avian polyomavirus (APV) and psittacine beak and feather disease virus (PBFDV) induce contagious and persistent diseases that affect the beaks, feathers, and immune systems of companion birds. APV causes hepatitis, ascites, hydropericardium, depression, feather disorders, abdominal distension, and potentially death. PBFDV can induce progressive beak deformity, feather dystrophy, and plumage loss. We conducted the first prevalence survey of both APV and PBFDV infections in companion birds in eastern Turkey.

Material and Methods

A total of 113 fresh dropping samples from apparently healthy companion birds were collected in a random selection. The dropping samples were analysed for PBFDV and APV by PCR. Positive samples were sequenced with the Sanger method. The sequence was confirmed through alignment and the phylogenetic tree generated through the maximum likelihood method computationally.

Results

PBFDV and APV were detected in a respective 48.7% and 23.0% of samples. Coinfection was found in 12.4% of the samples, these all being from budgerigars (Melopsittacus undulatus). APV and PBFDV were detected in budgerigar and cockatiel (Nymphicus hollandicus) samples.

Conclusion

This report provides a foundation for future studies on the influence of these viruses on the health of companion birds. These high positive rates for both pathogens emphasise that healthy M. undulatus and N. hollandicus in eastern Turkey may be prone to the emergence and spread of APV and PBFDV with subclinical potential.

Metatranscriptomic Analysis of Virus Diversity in Urban Wild Birds with Paretic Disease

Wildlife naturally harbor a diverse array of infectious microorganisms and can be a source of novel diseases in domestic animals and human populations. Using unbiased RNA sequencing, we identified highly diverse viruses in native birds from Australian urban environments presenting with paresis. This research included the clinical investigation and description of poorly understood recurring syndromes of unknown etiology: clenched claw syndrome and black and white bird disease. As well as identifying a range of potentially disease-causing viral pathogens, this study describes methods that can effectively and efficiently characterize emergent disease syndromes in free-ranging wildlife and promotes further surveillance for specific pathogens of potential conservation and zoonotic concern.

Wild birds are major natural reservoirs and potential dispersers of a variety of infectious diseases. As such, it is important to determine the diversity of viruses they carry and use this information to help understand the potential risks of spillover to humans, domestic animals, and other wildlife. We investigated the potential viral causes of paresis in long-standing, but undiagnosed, disease syndromes in wild Australian birds. RNA from diseased birds was extracted and pooled based on tissue type, host species, and clinical manifestation for metagenomic sequencing. Using a bulk and unbiased metatranscriptomic approach, combined with clinical investigation and histopathology, we identified a number of novel viruses from the families Astroviridae, Adenoviridae, Picornaviridae, Polyomaviridae, Paramyxoviridae, Parvoviridae, and Circoviridae in common urban wild birds, including Australian magpies, magpie larks, pied currawongs, Australian ravens, and rainbow lorikeets. In each case, the presence of the virus was confirmed by reverse transcription (RT)-PCR. These data revealed a number of candidate viral pathogens that may contribute to coronary, skeletal muscle, vascular, and neuropathology in birds of the Corvidae and Artamidae families and neuropathology in members of the Psittaculidae. The existence of such a diverse virome in urban avian species highlights the importance and challenges in elucidating the etiology and ecology of wildlife pathogens in urban environments. This information will be increasingly important for managing disease risks and conducting surveillance for potential viral threats to wildlife, livestock, and human health.

IMPORTANCE Wildlife naturally harbor a diverse array of infectious microorganisms and can be a source of novel diseases in domestic animals and human populations. Using unbiased RNA sequencing, we identified highly diverse viruses in native birds from Australian urban environments presenting with paresis. This research included the clinical investigation and description of poorly understood recurring syndromes of unknown etiology: clenched claw syndrome and black and white bird disease. As well as identifying a range of potentially disease-causing viral pathogens, this study describes methods that can effectively and efficiently characterize emergent disease syndromes in free-ranging wildlife and promotes further surveillance for specific pathogens of potential conservation and zoonotic concern.

Prevalence of Aves Polyomavirus 1 and Beak and Feather Disease Virus From Exotic Captive Psittacine Birds in Chile

Avian polyomavirus disease and psittacine beak and feather disease (PBFD) are both contagious viral diseases in psittacine birds with similar clinical manifestations and characterized by abnormal feathers. To determine the prevalence of Aves polyomavirus 1 (APyV) and beak and feather disease virus (BFDV) in captive, exotic psittacine birds in Chile, feathers from 250 psittacine birds, representing 17 genera, were collected and stored during the period 2013-2016. Polymerase chain reaction testing was used to detect APyV and BFDV were detected in feather bulb samples. The results indicated that 1.6% (4/250) of the samples were positive for APyV, 23.2% (58/250) were positive to BFDV, and 0.8% (2/250) were positive to both APyV and BFDV. This is the first report, to our knowledge, of APyV and BFDV prevalence in captive, exotic psittacine birds in South America. Analysis of 2 Chilean partial sequences of the gene encoding agnoprotein 1a (APyV) and the replication-associated protein (BFDV) extends the knowledge of genomic variability for both APyV and BFDV isolates and their spectrum of hosts. No geographical marker was detected for the local isolates.

Monitoring of free-ranging and captive Psittacula populations in Western Europe for avian bornaviruses, circoviruses and polyomaviruses

Avian pathogens such as bornaviruses, circoviruses and polyomaviruses are widely distributed in captive collections of psittacine birds worldwide and can cause fatal diseases. In contrast, only little is known about their presence in free-ranging psittacines and their impact on these populations. Rose-ringed parakeets (Psittacula krameri) and Alexandrine parakeets (Psittacula eupatria) are non-native to Europe, but have established stable populations in parts of Western Europe. From 2012-2017, we surveyed free-ranging populations in Germany and France as well as captive Psittacula individuals from Germany and Spain for avian bornavirus, circovirus and polyomavirus infections. Samples from two out of 469 tested free-ranging birds (0.4%; 95% confidence interval [CI-95]: 0.1-1.5%) were positive for beak and feather disease virus (BeFDV), whereas avian bornaviruses and polyomaviruses were not detected in the free-ranging populations. In contrast, avian bornaviruses and polyomaviruses, but not circoviruses were detected in captive populations. Parrot bornavirus 4 (PaBV-4) infection was detected by RT-PCR in four out of 210 captive parakeets (1.9%; CI-95: 0.7-4.8%) from four different holdings in Germany and Spain and confirmed by detection of bornavirus-reactive antibodies in two of these birds. Three out of 160 tested birds (1.9%; CI-95: 0.5-5.4%) possessed serum antibodies directed against budgerigar fledgling disease virus (BuFDV). PaBV-4 and BuFDV were also detected in several psittacines of a mixed holding in Germany, which had been in contact with free-ranging parakeets. Our results demonstrate that Psittacula parakeets are susceptible to common psittacine pathogens and their populations in Western Europe are exposed to these viruses. Nevertheless, the prevalence of avian bornaviruses, circoviruses and polyomaviruses in those populations is very low.RESEARCH HIGHLIGHTS Psittacula parakeets are susceptible to bornavirus, circovirus and polyomavirus infection.Introduced Psittacula populations in Europe have been exposed to these viruses.Nevertheless, they may be absent or present at only low levels in free-ranging Psittacula populations.Free-ranging populations in Europe pose a minor threat of transmitting these viruses to captive Psittaciformes.

First detection and molecular characterization of avian polyomavirus in young parrots in Pakistan

Avian polyomavirus (APV) infection, also called as budgerigar fledgling disease (BFD) causes various health problems in many psittacine species which may cause untimely death. The aims of this study were to investigate, for the first time, the detection, molecular characterization and phylogenetic analysis of avian polyomavirus (APV) in Pakistani psittacine birds. In an aviary a disease similar to APV was found and 90% of the nestlings died within a few weeks. Seven to ten-day-old parrot nestlings (n = 3) from the aviary were presented with feather abnormalities, plumage defect and were clinically depressed. Birds died at 11th, 14th and 16th day of age. Samples of hearts, livers, spleen, feathers and kidneys were collected from the dead birds. Samples were analyzed for the presence of APV DNA by using PCR. APV VP1 gene was partially sequenced, and phylogenetic analysis was performed. The APV strain was similar to those previously reported in other areas of the world. The results of this investigation indicate presence of a high frequency of APV infections in psittacine birds in Pakistan.

Psittacid Adenovirus-2 infection in the critically endangered orange-bellied parrot (Neophema chrysogastor): A key threatening process or an example of a host-adapted virus?

Psittacid Adenovirus-2 (PsAdv-2) was identified in captive orange-bellied parrots (Neophema chrysogastor) during a multifactorial cluster of mortalities at the Adelaide Zoo, South Australia, and an outbreak of Pseudomonas aeruginosa septicaemia at the Tasmanian Department of Primary Industries, Parks, Water and Environment captive breeding facility, Taroona, Tasmania. This was the first time that an adenovirus had been identified in orange-bellied parrots and is the first report of PsAdv-2 in Australia. To investigate the status of PsAdv-2 in the captive population of orange-bellied parrots, 102 healthy birds from five breeding facilities were examined for the presence of PsAdv-2 DNA in droppings and/or cloacal swabs using a nested polymerase chain reaction assay. Additionally, eight birds released to the wild for the 2016 breeding season were similarly tested when they were recaptured prior to migration to be held in captivity for the winter. PsAdv-2 was identified in all breeding facilities as well as the birds recaptured from the wild. Prevalence of shedding ranged from 29.7 to 76.5%, demonstrating that PsAdv-2 is endemic in the captive population of orange-bellied parrots and that wild parrots may have been exposed to the virus. PsAdv-2 DNA was detected in both cloacal swabs and faeces of the orange-bellied parrots, but testing both samples from the same birds suggested that testing faeces would be more sensitive than cloacal swabs. PsAdv-2 was not found in other psittacine species housed in nearby aviaries at the Adelaide Zoo. The source of the infection in the orange-bellied parrots remains undetermined. In this study, PsAdv-2 prevalence of shedding was higher in adult birds as compared to birds less than one year old. Preliminary data also suggested a correlation between adenovirus shedding prevalence within the breeding collection and chick survival.

Beak and feather disease virus carriage by Knemidocoptes pilae in a sulphur-crested cockatoo (Cacatua galerita)

BACKGROUND

This paper describes the pathology associated with psittacine beak and feather disease in a wild sulphur-crested cockatoo with concurrent knemidocoptic mange, cestodiasis and mycotic encephalitis.

METHODS & RESULTS

Large numbers of Knemidocoptes pilae Lavoipierre and Griffiths, 1951 (Acari: Epidermoptidae, Knemidokoptinae) were identified in affected skin associated with enhanced expression of beak and feather disease virus (BFDV) determined by immunohistochemistry. Also, BFDV antigen was demonstrated in high concentration in the gut and faecal sacs of mites, raising the possibility of ectoparasites as fomites and vectors of BFDV transmission. Large numbers of Raillietina spp. cestodes were present in the intestines. Within the brain there was a focally extensive region of necrosis and inflammation associated with branching, septate, pigmented hyphae consistent with zygomycete fungal infection.

CONCLUSION

This case highlights the potential immunosuppressive effects of BFDV infection and its potential as a keystone pathogen in the Australian environment.

Avian viral surveillance in Victoria, Australia, and detection of two novel avian herpesviruses

Viruses in avian hosts can pose threats to avian health and some have zoonotic potential. Hospitals that provide veterinary care for avian patients may serve as a site of exposure of other birds and human staff in the facility to these viruses. They can also provide a useful location to collect samples from avian patients in order to examine the viruses present in wild birds. This study aimed to investigate viruses of biosecurity and/or zoonotic significance in Australian birds by screening samples collected from 409 birds presented to the Australian Wildlife Health Centre at Zoos Victoria’s Healesville Sanctuary for veterinary care between December 2014 and December 2015. Samples were tested for avian influenza viruses, herpesviruses, paramyxoviruses and coronaviruses, using genus- or family-wide polymerase chain reaction methods coupled with sequencing and phylogenetic analyses for detection and identification of both known and novel viruses. A very low prevalence of viruses was detected. Columbid alphaherpesvirus 1 was detected from a powerful owl (Ninox strenua) with inclusion body hepatitis, and an avian paramyxovirus most similar to Avian avulavirus 5 was detected from a musk lorikeet (Glossopsitta concinna). Two distinct novel avian alphaherpesviruses were detected in samples from a sulphur-crested cockatoo (Cacatua galerita) and a tawny frogmouth (Podargus strigoides). Avian influenza viruses and avian coronaviruses were not detected. The clinical significance of the newly detected viruses remains undetermined. Further studies are needed to assess the host specificity, epidemiology, pathogenicity and host-pathogen relationships of these novel viruses. Further genome characterization is also indicated, and would be required before these viruses can be formally classified taxonomically. The detection of these viruses contributes to our knowledge on avian virodiversity. The low level of avian virus detection, and the absence of any viruses with zoonotic potential, suggests low risk to biosecurity and human health.

High prevalence of Mycobacterium genavense within flocks of pet birds

Mycobacterium genavense is regarded as the primary cause of mycobacteriosis in psittaciform and passeriform birds, which are commonly kept as pets. In humans, Mycobacterium genavense is especially pathogenic for young, old, pregnant and immunocompromised people (YOPIs). In birds, only few studies, mainly case reports, exist and there is still little e information about occurrence and relevance of this zoonotic pathogen. In this first pilot study concerning the prevalence of Mycobacterium genavense within flocks of naturally infected pet birds, real-time PCR examinations of 170 individual passeriform and psittaciform birds, including commonly kept budgerigars, lovebirds and zebra finches as well as gold finches and weaver finches, were conducted to determine the infection rate in six different aviaries. Antemortem examinations of faeces and cloacal swabs were compared with postmortem examinations of tissue samples to evaluate the reliability of antemortem diagnostics. Additional ophthalmologic examinations were performed to evaluate their diagnostic potential. Molecular examinations for viral co-infections, including circovirus, polyomavirus and adenovirus, were conducted to identify potential risk factors. PCR results revealed a detection prevalence of Mycobacterium genavense in the flocks varying from 3% to 91% based on postmortem testing, while antemortem diagnostics of faecal samples and swabs showed 64% discrepant (false negative) results. Ophthalmologic examinations were not useful in identifying infected birds within the flocks. Viral co-infections, especially with polyomavirus, were common. It has to be assumed that Mycobacterium genavense infections are widespread and underdiagnosed in companion birds. Viral infections might be an important risk factor. There is urgent need to improve antemortem diagnostics.